<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			// 测试题1:先执行变量提升，再执行函数提升
			function a() {}
			var a;
			console.log(typeof a)//'function'
			
			// 测试题2
			if(!(b in window)){
				var b = 1;
			}
			console.log(b) //undefined
			
			// 测试题3:
			var c = 1
			function c(c){
				console.log(c)
			}
			c(2) //报错
		</script>
	</body>
</html>
